1. Field of the Invention
The invention relates to voltage generation and, more particularly, to voltage generation internal to memory systems.
2. Description of the Related Art
Memory cards are commonly used to store digital data for use with various products (e.g., electronics products). Examples of memory cards are Flash cards that use Flash type or EEPROM type memory cells to store the data. Flash cards have a relatively small form factor and have been used to store digital data for products such as cameras, hand-held computers, set-top boxes, hand-held or other small audio players/recorders (e.g., MP3 devices), and medical monitors. A major supplier of Flash cards is SanDisk Corporation of Sunnyvale, Calif.
FIG. 1 is a schematic diagram of a conventional voltage regulation circuit 100. The conventional voltage generation circuit 100 can provide a regulated voltage to a memory system that provides non-volatile data storage and represents, for example, a memory card (e.g., Flash card). The conventional voltage regulation circuit 100 includes an amplifier 102 that couples to a supply voltage (Vcc) and outputs a regulated voltage (Vdd) at output terminal 104. A resistor divider 106 is coupled to the output terminal 104. The resistor divider 106 includes resistors RI and R2. A feedback voltage (Vfb) is fed back from the resistor divider 106 to an input to the amplifier 102. Another input to the amplifier 102 is a reference voltage (Vref). The conventional voltage regulation circuit 100 also includes a decoupling capacitor 108 (Cd) coupled to the output terminal 104.
The voltage regulation circuit 100 regulates the supply voltage (Vcc) downward to produce the output voltage (Vdd). The downward regulation helps produce a more stable output voltage (Vdd) as compared to the supply voltage (Vcc). The decoupling capacitor 108 is utilized to stabilize the voltage level at the output terminal. When a load is coupled to the output terminal, the load may draw substantially high current levels (i.e., surges) such that the output voltage (Vdd) is pulled significantly downward. The decoupling capacitor 108 can operate to supply current to the output terminal 104 when significant current is being drawn by the load.
Unfortunately, however, when a load coupled to the voltage regulation circuit 100 draws substantially high current levels, the decoupling capacitor 108 needs to have a relatively large capacitance to significantly stabilize the output voltage level in the presence of current surges. However, to provide such high capacitance requires a lot of die area within a semiconductor product. Given that die area utilization affects overall size and cost of the product, there is a need to provide improved approaches to stabilizing output voltage levels in the presence of high current surges.